Heat transfer apparatus



Sept. 19, 1939. J ms 2,173,169

HEAT TRANSFER APPARATUS Filed Feb. 15, 1936 5 Sheets-Shet 1 3/ XNVENTQRH 3 4% Z5 *5 4 ATTORNEYS Sept. 19, 1939. J. M. JENKINS HEAT TRANSFERAPPARATUS 5 Sheets-Sheet 2 Filed Feb. 15, .1936

' lNVENT Q- ATTORNEYS Sept. 19, 1939. J, M. JENKINS 7 HEAT TRANSFERAPPARATUS Filed Feb. 15, 1936 5 Sheets-Sheet 3 Liz..

INVENTOR ATTORNEYJ Patented Sept. 19, 1939 "PATENT OFFICE HEAT TRANSFERAPPARATUS James M. Jenkins, Philadelphia, Pa., assignor to AndaleCompany, Philadelphia, Pa., a corporation of PennsylvaniaApplicationFebruary 15, 1936, Serial No. 64,023

1 Claim.

This invention relates to heat transfer apparatus and is especiallyconcerned with equipment adapted for use in connection with the heatingor cooling of oil or similar liquid of a relatively 5 viscous natureand, broadly considered, it aims to improve the efllciency of heattransfer as well as to minimize or eliminate certain disadvantagesincident to apparatus heretofore in use, as will further appear.

The invention is particularly applicable to the heating of oil, forwhich reason the accompanying disclosure will relate primarily to itsusefulness in this field although, as will be apparent, certain featuresof the invention may be equally useful in cooling oil or a similarviscous liquid.

The improvements which I have developed are peculiarly applicable to theheating of rather small quantities of oil, preferably in theneighborhood of one to two gallons per minute and within a temperaturerange running up to approximately 180 F. or thereabouts, and theapparatus herein illustrated and described is primarily designed forthis class of service. It is useful, for example, in heating smallquantities 5 of lubricating oil in order to increase its fluidity forcentrifuging, or for the heating of fuel oil for domestic oil burners,or for use in Diesel engines, etc.

In considering the objects and advantages of the invention as theyappear hereinafter, it should be borne in mind that relatively viscousliquids, particularly oil, have a rather high"fi1m resistance, i. e., aresistance to the giving up or taking on of heat as compared with morefluid liquids such, for example, as water.

Among the objects of the invention, therefore, is the provision of. aheat transfer apparatus of the character described in which theresistance to heat transfer is markedly reduced by greatly 40 increasingthe turbulence of the viscous liquid over the area where the heattransfer is taking place.

. It is also an object of the invention to indirectly heat oil by meansof a relatively fluid medium, such as water, in which is immersed aheating unit, preferably electrical.

' A further object of the invention is to prevent carbonization of theoil on the heating surfaces and to make possible a heater in which theoil side can be readily cleaned.

Another object of the invention is to eliminate all fire hazard in adevice of this kind, as well as to provide a heating unit which willprevent any overheating of the oil, in connection with 56 which latterObject it is a further aim of the invention to avoid any burning oroverheating of the oil regardless of the quantity of oil which may begoing through the heater or the slowness of its flow.

Another object of the invention is to provide a heater which will serveto clean the oil of foreign particles and dirt of one kind or another.

Somewhat more specifically stated, the invention contemplates the use ofwater or some other relatively fluid liquid as the heat transfer medium,which medium is heated directly by a heating element, preferablyelectrical.

How the foregoing objects and advantages are attained will be broughtout more fully in connection with the following description referring tothe accompanying drawings, in which Figure 1 is a vertical sectionalview of a heat exchanger constructed in accordance with this invention,taken as indicated by the section line |l on Figure 2;

Figure 2 is also a. vertical sectional view, but taken approximately atright angles to the section of Figure 1;

Figure 3 is a top plan view of the equipment; and

Figure 4 is a horizontal sectional view taken as shown by the sectionline 4-4 on Figure 1.

The unit shown includes a shell 5 which may conveniently be of tubularshape and molded with lagging 6 for insulation purposes. A bottom endclosure 1 and a top closure 8 define the end walls of a chamber adaptedto receive the heat transfer medium, the upper level of which appears atW in Figure 1.

The heat transfer medium is heated preferably by an electrical heatingelement 9 which may conveniently project upwardly through the bottomclosure 1. The heater may be in part surrounded by a baflle Ill servingto define a channel through which the medium circulates duringoperation. A vent H may be provided at the top of the chamber, and watermay be introduced into the chamber by removal of the cap I! serving toclose the upper end of a tube l3 preferably formed as a gauge glass. Athermostat 9a is provided for the purpose of shutting off the currentshould the temperature rise above a predetermined limit say, forexample, 200 F.

The present embodiment also employs a float ll for controlling thecurrent, which float is mounted for vertical movement as by stems l5 andIS, the stem l6 serving to actuate a switch H in the heating circuit forthe element 9. The detailsof this switch form no part of the presentinvention per se, although it is mentioned that upon a drop in the waterlevel and a consequent drop of the float I4, the switch I! is actuatedto break the heating circuit. Thus the equip ment will not operate ifthe water level drops below a predetermined point.

It will be obvious that either the float alone or the thermostat aloneor both together may be provided, and I do not Wish to be limited to anyparticular means for shutting off the current. If both devices areadopted they may be interrelated in such a way that the float exerts theprimary control with the thermostat arranged to function only in case ofa failure of the float.

An oil flow tube I8, preferably of copper, with its end portionsprojecting through the heads I and 8 and bent over, as shown, ispositioned within the chamber so as to be surrounded by the watertherein. The tube is provided with connection members 19 and 20, theformer of which is provided with an inlet 2| and the latter with anoutlet 22. The connection members are attached by bolts such as shown atMain Figure 3. Caps 23 serve to close the ends of the oil tube and maybe tightened in position as by means of yokes 24 and hand screws 25.

Within the tube I 8 I position a core which may conveniently be built upon a rod 26 by alternately stacking a multiplicity of annular fins 21and spacing washers 28. This core is centrally located in the tube l8with slight clearance between the peripheral edges of the fins and theinside wall of the tube. The several fins and spacer members maybetightened by means of nuts 29 threaded onto the ends of rod 26. Rodextensions 30 cooperate with suitable recesses formed on the insidefaces of the end caps 23 in order to ensure proper positioning of thecore.

in use the equipment is operated in substantially the following manner:

First, the chamber within the shell 5 is supplied with water, and thiswater is heated by means of the heater 9. Oil is then caused to flowfrom the inlet 2| to the outlet 22. This flow, of course, takes placearound the edges of the fins 21, which are positioned in planes at anangle, preferably a right angle, to the general direction of flow and,therefore, set up intensive turbulence or eddying around the edges ofthe fins.

While I have found that indirect transfer of heat from the heaterelement 9 or equivalent device through the water or equivalent medium,to the oil is of advantage in improving heat transfer to a viscousliquid, it is pointed out that the present invention furthercontemplates the use of a means, such as the fins 21 within the tube l8,for creating a high degree of turbulence in the oil during the time itis passing in heat transfer relation with respect to the medium. I havefound that this condition of turbulence is of great importance insecuring the desired high rate of heat transfer, because a mere increasein velocity in flow does not accomplish the improvement effected inaccordance with this invention.

In addition to the foregoing, tests have shown that the degree ofturbulence preferably should pass a certain critical. value in order tofully attain the objects of this invention. In order to attainturbulence at or above the critical value,

the equipment may have to be modified in accordance with the pressureand the volume of oil a cleaning operation.

passed through the equipment per unit of time, although I have foundthat for a heater having a capacity of from one to two gallons perminute where the oil is heated to a temperature between and F. verysatisfactory operation can be attained by using an oil tubeapproximately three inches in diameter with the plates 21 aboutone-sixteenth of an inch thick, with a spacing between alsoapproximately one-sixteenth of an inch in size, and with approximatelyone-thirtysecond of an inch clearance between the perimeter of eachplate and the adjacent wall of the tube.

I wish it to be distinctly understood, however, that the severaldimensions given above might have to be varied slightly to suitindividual conditions, and I do not wish to be limited thereto. Theprincipal point to consider is that the ef fectiveness of heat transferfrom or to a viscous liquid seems to bear rather a direct relation tothe turbulence of the viscous liquid at the surface where the transferis taking place. In any event, whatever the theory involved may be, Ihave found that the eflloiency of a device of this character is greatlyincreased where the turbulence of the viscous liquid is greatlyincreased. With my improved device I have found that the rate of heattransfer from or. to the viscous liquid may be raised to a pointapproximately as high as that of a relatively fluid liquid, such aswater.

It will be seen that my improved heater is practically foolproof, thatis, no matter of what carelessness the attendant may be guilty, nodamage can result. Even should all the water boil away, the heater willnot be particularly damaged except possibly for the heating unit 9which, of course, may burn out in such event. No explosion can takeplace because of the vent I I, nor is there any fire hazard. ,The oilcan not be burned nor overheated and no carbon can form on any of theheating surfaces. My invention, therefore, makes it possible to entirelyobviate the necessity of using the various safety devices ordinarilyprovided for the protection of prior oil heating equipment.

Among other things I have found that the particular turbulence creatingmeans which I employ, namely, the spaced baiiie plates 21 exert a markedcleaning effect upon the oil, small particles of suspended dirt or otherforeign matter having a tendency to work themselves down into the spacesbetween the plates where they accumulate until such time as the unit isremoved for In other words, it might be said that my improved apparatusfunctions as a combined heater and cleaner.

I claim:

A heat exchange device for use with viscous liquids, including a tubethrough which the viscous liquid is passed, said tube having amultiplicity of spaced baffles lying in planes at an angle to thedirection of flow of the viscous liquid, the baffles being arranged toprovide flow space for the viscous liquid across their peripheral edgesadjacent the tube wall, a core member on which said baffles are mounted,and removable cap means at one end thereof, said core being posi- JAMESM. JENKINS.

